OpenSees allows users to create finite element applications for simulating the response of structural and geotechnical systems subjected to earthquakes.

This framework was developed by Frank McKenna and Gregory L. Fenves with significant contributions from Michael H. Scott, Terje Haukaas, Armen Der Kiureghian, Remo M. de Souza, Filip C. Filippou, Silvia Mazzoni, and Boris Jeremic.

The license permits the use, reproduction, modification, and distribution by educational, research, and non-profit entities for non-commercial purposes.

[1] Users of OpenSees create applications by writing scripts in either the Tcl or Python programming language.

Prior to taking on the name "OpenSees," the framework was simply called "G3" in reference to the name of the PEER research group tasked with simulation development.